<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    //定义没有参数列表,也没有返回值的函数
    function hello(){
        console.log("hello")
    }
    //函数调用
   let b= hello();

    console.log(b)//undefined
    
    console.log("=======================")
    //定义有参数列表,有返回值的函数
    function add(a,b){
        return a+b;
    }
      let a =add(1,2)
      console.log(a)
      console.log(typeof(a))//number

</script>
</html>